undefined reference to 'QScriptEngine::QScriptEngine()

undefined reference to 'QScriptEngine::QScriptEngine()

Given this code, I get: "undefined reference to
'QScriptEngine::QScriptEngine()"
#include <QtScript/QScriptEngine>
...
QScriptEngine e;
/* Commented out to understand the instantiation error first
e.globalObject().setProperty("t", 123);
bool result = e.evaluate("(t>=2 && t<5) || (t<1)").toBool();
*/